What Is a CDN and What Does It Do for Your Website?
A CDN (content delivery network) is a globally distributed group of servers that caches and serves your website's content from locations close to each user. It speeds up load times, reduces load on your origin server, cuts bandwidth costs, and absorbs some attack traffic. You need one when visitors are geographically spread out, your origin struggles under traffic, or you want a layer of protection and performance without rebuilding your application. Akamai, for example, describes itself as a cybersecurity and cloud computing company that delivers and protects content online — a useful reminder that modern CDNs are usually bundled with security and edge compute, not sold as caching alone.
How a CDN actually works
The mechanism is straightforward:
- You point your domain at the CDN — usually by changing DNS records or adding a CNAME so requests resolve to the CDN's edge network instead of directly to your origin.
- A user requests a file (an image, script, page, or video segment).
- The nearest edge server answers. If it already has a valid cached copy, it returns it immediately — a cache hit.
- On a miss, the edge fetches from your origin, stores a copy according to your caching rules, and serves it to the user.
- Subsequent users near that edge get the cached copy, so your origin is hit far less often.
The distance between user and server is the core idea: physics limits how fast data travels, so serving from a nearby edge is faster than serving everything from one origin region.
What it does for your website
| Benefit | What it means in practice |
|---|---|
| Faster load times | Content arrives from a nearby edge instead of a distant origin |
| Reduced origin load | Cached requests never reach your server, freeing capacity |
| Bandwidth savings | Offloaded traffic can lower egress costs |
| Basic DDoS absorption | Distributed edge capacity can soak up volumetric traffic |
| Availability | Cached content can keep serving if the origin is briefly unavailable |
The DDoS point deserves a caveat: a CDN absorbs and distributes traffic, but full protection usually comes from a dedicated security layer (see below), not caching alone.
CDN vs. cloud computing, WAF, and edge platforms
These terms overlap and are often sold together, so it helps to separate them:
- CDN — caches and delivers content from edge locations. Its job is speed and offload.
- Cloud computing — provides compute, storage, and services in centralized (or regional) data centers. It runs your application; a CDN sits in front of it.
- WAF (web application firewall) — inspects HTTP traffic and blocks attacks like SQL injection or cross-site scripting. Many CDNs include a WAF, but the functions are distinct.
- Edge platform — runs code (serverless functions, logic) at the edge, closer to users than a central cloud region. It extends the CDN from serving content to processing requests.
A single vendor may offer all four. When comparing providers, check which capabilities are included versus added on.
How to put your site behind a CDN
- Choose a provider based on where your users are, what's included (security, edge compute), and pricing for your regions. Akamai publishes region-specific pricing pages (North America, Europe, Asia Pacific, South America, Jakarta), so you can compare costs by geography rather than assume one global rate.
- Add your domain in the provider's dashboard and verify ownership.
- Change DNS or add a CNAME so traffic routes through the CDN. This is the step that actually puts you "behind" it.
- Configure caching rules — set what's cached, for how long (TTL), and what must always hit the origin (e.g., logged-in pages, checkout).
- Set up SSL/TLS so HTTPS works end to end.
- Test with your browser's network tools or a command-line check to confirm content is served from edge locations and headers show cache hits.
Common problems and what to check
- Stale content — your TTL is too long or you haven't purged the cache after a deploy. Shorten TTLs for frequently updated assets and purge on release.
- Cache misses — caching rules may exclude the content, or query strings and cookies may be fragmenting the cache. Review what varies the cache key.
- SSL errors — certificate mismatch between edge and origin, or an incomplete chain. Verify both legs of the connection.
- Wrong content for logged-in users — personalized pages should bypass the cache; caching them can leak one user's data to another.
Deciding whether you need one
You likely benefit if your audience is geographically distributed, your origin is a bottleneck, or you want performance and protection without re-architecting. A single-region site with a local audience may see less gain. Before committing, confirm what's bundled (security, edge compute), how pricing varies by region, and whether the provider's edge locations actually cover where your users are — that coverage, more than any feature list, determines the real-world benefit.